Solventless radiation curable stretchable ink composition

ABSTRACT

A solventless radiation curable stretchable ink composition including an aliphatic urethane monomer or oligomer; an acrylic ester monomer; a photoinitiator; and an optional colorant. A patterned article including a deformable substrate; an image printed on the deformable substrate, the image being formed from a radiation curable stretchable ink composition comprising an aliphatic urethane monomer or oligomer; an acrylic ester monomer; a photoinitiator; and an optional colorant.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Ser.No. 61/849,815, filed Feb. 6, 2013, which is hereby incorporated byreference herein in its entirety.

Commonly assigned U.S. patent application Ser. No. 13/957,213, entitled“Stretchable Ink Composition”, filed concurrently herewith, with thenamed inventors Yiliang Wu, Cameron Derry, and Ke Zhou, is herebyincorporated by reference herein in its entirety.

Commonly assigned U.S. patent application Ser. No. 13/957,374, entitled“Stretchable Ink Composition”, with the named inventors Yiliang Wu andCameron Derry, filed concurrently herewith, is hereby incorporated byreference herein in its entirety.

BACKGROUND

Disclosed herein is a solventless radiation curable stretchable inkcomposition including an aliphatic urethane monomer or oligomer; anacrylic ester monomer; a photoinitiator; and an optional colorant.Further disclosed is a patterned article including a deformablesubstrate; an image printed on the deformable substrate, the image beingformed from a radiation curable stretchable ink composition comprisingan aliphatic urethane monomer or oligomer; an acrylic ester monomer; aphotoinitiator; and an optional colorant.

Printing marks or images on deformable substrates is desirable for manyapplications, such as flexible medical devices, including surgical toolsand implantable medical devices, robot skins, textiles (e.g., forstretchable swimming suits), rubber products such as tires, tubes, andcables, and the like. Consumable products based on rubbers and sometextiles are also stretchable. Because of the highly deformablecharacteristic of the substrate, a stretchable ink is desired forprinting on such substrates to achieve excellent image quality, imagerobustness, and image longevity.

Previous work by the inventors includes a stretchable ink compositionwhich comprises water, a colorant, a surfactant, and a fluoroelastomer,as disclosed in U.S. patent application Ser. No. 13/182,579 to Wu etal., filed on Jul. 14, 2011, which is hereby incorporated by referenceherein in its entirety.

U.S. patent application Ser. No. 13/495,915, which is herebyincorporated by reference herein in its entirety, of Wu et al.,describes in the Abstract thereof an ink composition suitable for inkjet printing, including printing on deformable substrates. Inembodiments, the stretchable ink composition is based on an aqueous inkformulation comprising an emulsion of a polyurethane elastomer incombination with colorant dispersions, and surfactants.

While known compositions and processes are suitable for their intendedpurposes, a need remains for improved ink compositions with certaincharacteristics. Specifically, a need remains for ink compositionssuitable for printing on deformable or stretchable substrates.Additionally, a need remains for stretchable inks that form robustimages which can be stretched and relaxed for a high number of cycles.There is also a need for stretchable inks that have good colorstability. There is also a need for stretchable inks that exhibit goodresistance to environmental factors such as light, chemicals, water, andoxidizing gases, thus generating hydrophobic and water-resistant images.There further remains a need for stretchable inks that are suitable forboth indoor and outdoor applications. There further remains a need forsuch inks can be applied digitally.

The appropriate components and process aspects of the each of theforegoing U.S. Patents and Patent Publications may be selected for thepresent disclosure in embodiments thereof. Further, throughout thisapplication, various publications, patents, and published patentapplications are referred to by an identifying citation. The disclosuresof the publications, patents, and published patent applicationsreferenced in this application are hereby incorporated by reference intothe present disclosure to more fully describe the state of the art towhich this invention pertains.

SUMMARY

Described is a solventless radiation curable stretchable ink compositionincluding an aliphatic urethane monomer or oligomer; an acrylic estermonomer; a photoinitiator; and an optional colorant.

Also described is a patterned article including a deformable substrate;an image printed on the deformable substrate, the image being formedfrom a solventless radiation curable stretchable ink compositioncomprising an aliphatic urethane monomer or oligomer; an acrylic estermonomer; a photoinitiator; and an optional colorant.

DETAILED DESCRIPTION

A solventless radiation curable stretchable ink composition is providedincluding an aliphatic urethane monomer or oligomer; an acrylic estermonomer; a photoinitiator; and an optional colorant.

The stretchable monomer-based ink compositions herein provide goodelongation after curing, low viscosity for ink jet printing, low or notackiness on the surface, and wide substrate latitude includingexcellent adhesion on silicon and latex rubber substrates. Inembodiments, the ink compositions herein comprise a combination ofoligomer and monomer components, in embodiments, 1) a mixture ofaliphatic urethane oligomer and acrylic ester in combination with anacryloxyalkylsilane or 2) a mixture of aliphatic urethane oligomer andacrylic ester in combination with an acrylic oligomer havingmethacrylate acid ester, acrylic ester and aromatic urethane acrylate,and combinations thereof.

As used herein, “solventless” radiation curable stretchable ink meansthat “the absence of an organic solvent;” that is, organic solvents arenot used to dissolve the monomer or oligomer components of the ink orare not used as the ink vehicle. However, it is understood that minoramounts of such solvents may be present in the resins as a consequenceof their use in the process of forming the resin.

The solventless radiation curable stretchable ink composition can be inkjet printed onto various deformable substrates, such as for example, astretchable latex rubber substrate, to provide an image having imagelongevity. The printed images exhibit superior performance on thedeformable substrates, which are generally difficult to print upon.

In embodiments, the solventless radiation curable stretchable inkcomposition can be used to prepare a patterned article. In embodiments,a patterned article is provided comprising a deformable substrate; animage printed on the deformable substrate, the image being formed from asolventless radiation curable stretchable ink composition comprising analiphatic urethane monomer or oligomer; an acrylic ester monomer; and anoptional colorant.

In embodiments, the solventless radiation curable stretchable inkcomposition herein has a low viscosity which is compatible with inkjetprinting methods. The printed solventless radiation curable stretchableink provided herein can form robust images on a variety of substrateincluding normal paper, coated photo paper, and rubber substrate.Moreover, in embodiments, images printed with the solventless radiationcurable stretchable ink herein can be stretched hundreds of cycleswithout showing any crack and de-lamination, when printed on adeformable substrate, in embodiments, a rubber substrate.

Monomers and Oligomers.

Aliphatic Urethane Monomer or Oligomer and Acrylic Ester Monomer.

The radiation curable stretchable ink composition comprises one or morealiphatic urethane monomers or oligomers.

The solventless stretchable ink composition herein is based on a monomerapproach. The inks herein meet several challenges and requirements formonomer based stretchable ink jettable ink, including 1) good elongationafter curing, 2) low viscosity for inkjet printing, 3) low or notackiness on the surface, and 4) wide substrate latitude. A selectedcombination of hard and soft segments is provided which achieves goodelongation. Therefore, the selected monomers or oligomers used hereinprovided, in combination, a crosslinking density that provides goodelongation. Oligomers can have a high viscosity which is not suitablefor inkjet printing. The present solventless ink composition provides acombination that reduces viscosity to a jettable range while stillemploying oligomers. The final cured ink has a glass transitiontemperature (Tg) that is less than room temperature for elongation.Usually, a low Tg component is very tacky at room temperature. Thepresent solventless ink composition reduces or eliminates tackiness.Unlike printing on paper which has high surface energy, rubbersubstrates such as silicon rubber generally have a low surface energy.The present solventless ink compositions provided good adhesion to manydifferent substrates, including rubber substrates. The solventless inkcompositions herein comprise a combination of oligomer and monomercomponents. In embodiments, the solventless ink compositions comprises amixture of aliphatic urethane oligomer and acrylic ester in combinationwith acryloxyalkylsilane or acrylic oligomer comprising a member of thegroup consisting of methacrylate acid ester, acrylic ester, aromaticurethane acrylate, and combinations thereof. The inks provide goodelongation, non-tacky surface, and excellent adhesion on silicon andlatex rubber substrates.

In embodiments, the aliphatic urethane monomer or oligomer can comprisean aliphatic urethane/tackifier oligomer available as Sartomer CN3001.

In embodiments, the aliphatic urethane monomer or oligomer may bepresent in the ink in any desired or effective amount. In specificembodiments, the aliphatic urethane monomer or oligomer is present in anamount of from about 15 to about 50 weight percent, or from about 20 toabout 45 weight percent, or from about 25 to about 40 weight percent,based on the total weight of the solventless radiation curablestretchable ink composition.

In embodiments, the acrylic ester monomer can comprise an acrylic esteravailable as Sartomer CD420.

In embodiments, the acrylic ester monomer may be present in the ink inany desired or effective amount. In specific embodiments, the acrylicester monomer is present in an amount of from about 30 to about 70percent, or from about 30 to about 60 percent, or from about 35 to about60 percent, by weight, based on the total weight of the solventlessradiation curable stretchable ink composition.

Acryloxyalkylsilane.

In certain embodiments, the radiation curable stretchable inkcomposition comprises a mixture of aliphatic urethane oligomer andacrylic ester in combination with an acryloxyalkylsilane.

Acryloxyalkylsilane can have the general formulaCH₂═CROO—R′_(a)—R″—SiX₃

wherein R is a methyl radical or a hydrogen atom, R′ is a divalent groupcomposed of carbon, hydrogen, and oxygen, wherein the oxygen is in aconfiguration selected from the group consisting of ether linkages andhydroxyl groups, and wherein in R′ the ratio of carbon atoms to oxygenatoms is not greater than 3 to 1, and R′ is attached to both the COO andthe R″ groups through CO linkages, a has a value of 0 or 1, R″ is analkylene radical of from 1 to 4 carbon atoms, and X is a monovalenthydrolysable group. Acryloxyalkylsilanes have been described in U.S.Pat. No. 3,258,477, which is hereby incorporated by reference herein inits entirety. In embodiments, the acryloxyalkylsilane can comprise anacryloxyalkylsilane available as Sartomer CN3105.

In embodiments, the acryloxyalkylsilane may be present in the ink in anydesired or effective amount. In specific embodiments, theacryloxyalkylsilane is present in an amount of from about 5 to about 20weight percent, or from about 8 to about 15 weight percent, based on thetotal weight of the solventless radiation curable stretchable inkcomposition.

Acrylic Oligomer.

In certain other embodiments, the radiation curable stretchable inkcomposition comprises a mixture of aliphatic urethane oligomer andacrylic ester in combination with an acrylic oligomer. In embodiments,the acrylic oligomer comprises a member of the group consisting ofmethacrylate acid ester, acrylic ester, aromatic urethane acrylate, andcombinations thereof. In embodiments, the acrylic oligomer is an acrylicoligomer with methacrylate acid ester, acrylic ester, and aromaticurethane acrylate available as Sartomer CN3105.

In embodiments, the acrylic oligomer may be present in the ink in anydesired or effective amount. In specific embodiments, the acrylicoligomer is present in an amount of from about 5 to about 30 weightpercent, or from about 10 to about 25 percent, or from about 10 to about20 percent, by weight, based on the total weight of the solventlessradiation curable stretchable ink composition.

In embodiments, the aliphatic urethane monomer or oligomer present in anamount of from about 15 to about 50 weight percent based on the totalweight of the ink composition; the acrylic ester monomer present in anamount of from about 30 weight percent to about 70 weight percent basedon the total weight of the ink composition; an acrylic oligomer presentin an amount of from about 5 weight percent to about 30 weight percentbased on the total weight of the ink composition; and anacryloxyalkylsilane present in an amount of from about 5 weight percentto about 20 weight percent based on the total weight of the inkcomposition.

Photoinitiator.

The solventless radiation curable stretchable ink composition mayoptionally include an initiator, such as, for example, a photoinitiator.Such an initiator is desirable for assisting in curing of the ink. Inembodiments, a photoinitiator that absorbs radiation, for exampleultra-violet (UV) light radiation, to initiate curing of the curablecomponents of the ink may be used. Therefore, in embodiments, theradiation curable stretchable ink composition is an ultra-violetradiation curable ink composition. As the photoinitiator for inkcompositions that are cured by free-radical polymerization, forinstance, ink compositions containing acrylate groups or inks comprisedof polyamides, mention may be made of photoinitiators such asbenzophenones, benzoin ethers, benzil ketals, α-hydroxyalkylphenones,α-alkoxyalkylphenones α-aminoalkylphenones and acylphosphinephotoinitiators sold under the trade designations of IRGACURE® andDAROCUR® from Ciba. Specific examples of suitable photoinitiatorsinclude 2,4,6-trimethylbenzoyldiphenylphosphine oxide (available as BASFLUCIRIN® TPO); 2,4,6-trimethylbenzoylethoxyphenylphosphine oxide(available as BASF LUCIRIN® TPO-L);bis(2,4,6-trimethylbenzoyl)-phenyl-phosphine oxide (available as CibaIRGACURE® 819) and other acyl phosphines;2-methyl-1-(4-methylthio)phenyl-2-(4-morpholinyl)-1-propanone (availableas Ciba IRGACURE® 907) and1-(4-(2-hydroxyethoxy)phenyl)-2-hydroxy-2-methylpropan-1-one (availableas Ciba IRGACURE® 2959); 2-benzyl 2-dimethylamino1-(4-morpholinophenyl)butanone-1 (available as Ciba IRGACURE® 369);2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)-benzyl)-phenyl)-2-methylpropan-1-one(available as Ciba IRGACURE® 127);2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-ylphenyl)-butanone(available as Ciba IRGACURE® 379); titanocenes; isopropylthioxanthone;1-hydroxy-cyclohexylphenylketone; benzophenone;2,4,6-trimethylbenzophenone; 4-methylbenzophenone;diphenyl-(2,4,6-trimethylbenzoyl) phosphine oxide;2,4,6-trimethylbenzoylphenylphosphinic acid ethyl ester;oligo(2-hydroxy-2-methyl-1-(4-(1-methylvinyl)phenyl)propanone);2-hydroxy-2-methyl-1-phenyl-1-propanone; benzyl-dimethylketal; andmixtures thereof. Mention may also be made of amine synergists, whichare described as co-initiators that donate a hydrogen atom to aphotoinitiator and thereby form a radical species that initiatespolymerization (amine synergists can also consume oxygen dissolved inthe ink—as oxygen inhibits free-radical polymerization its consumptionincreases the speed of polymerization), for example such asethyl-4-dimethylaminobenzoate and 2-ethylhexyl-4-dimethylaminobenzoate.This list is not exhaustive, and any known photoinitiator that initiatesthe free-radical reaction upon exposure to a desired wavelength ofradiation such as UV light can be used without limitation.

The photoinitiator may absorb radiation of about 200 to about 420nanometers wavelengths in order to initiate cure, although use ofinitiators that absorb at longer wavelengths, such as the titanocenesthat may absorb up to 560 nanometers, can also be used withoutrestriction.

The photoinitiator can be present in any suitable or desired amount. Inembodiments, the total amount of initiator included in the solventlessradiation curable stretchable ink composition may be from, for example,about 0.5 to about 15 percent by weight, or from about 1 to about 10percent by weight, based on the total weight of the ink composition.

Colorant.

The stretchable ink composition herein may also contain a colorant. Anysuitable or desired colorant can be used in embodiments herein,including pigments, dyes, and mixtures and combinations thereof.

As noted, any suitable or desired colorant can be selected inembodiments herein. The colorant can be a dye, a pigment, or a mixtureor combination thereof. Examples of suitable dyes include anionic dyes,cationic dyes, nonionic dyes, zwitterionic dyes, and the like. Specificexamples of suitable dyes include Food dyes such as Food Black No. 1,Food Black No. 2, Food Red No. 40, Food Blue No. 1, Food Yellow No. 7,and the like, FD & C dyes, Acid Black dyes (No. 1, 7, 9, 24, 26, 48, 52,58, 60, 61, 63, 92, 107, 109, 118, 119, 131, 140, 155, 156, 172, 194,and the like), Acid Red dyes (No. 1, 8, 32, 35, 37, 52, 57, 92, 115,119, 154, 249, 254, 256, and the like), Acid Blue dyes (No. 1, 7, 9, 25,40, 45, 62, 78, 80, 92, 102, 104, 113, 117, 127, 158, 175, 183, 193,209, and the like), Acid Yellow dyes (No. 3, 7, 17, 19, 23, 25, 29, 38,42, 49, 59, 61, 72, 73, 114, 128, 151, and the like), Direct Black dyes(No. 4, 14, 17, 22, 27, 38, 51, 112, 117, 154, 168, and the like),Direct Blue dyes (No. 1, 6, 8, 14, 15, 25, 71, 76, 78, 80, 86, 90, 106,108, 123, 163, 165, 199, 226, and the like), Direct Red dyes (No. 1, 2,16, 23, 24, 28, 39, 62, 72, 236, and the like), Direct Yellow dyes (No.4, 11, 12, 27, 28, 33, 34, 39, 50, 58, 86, 100, 106, 107, 118, 127, 132,142, 157, and the like), Reactive Dyes, such as Reactive Red Dyes (No.4, 31, 56, 180, and the like), Reactive Black dyes (No. 31 and thelike), Reactive Yellow dyes (No. 37 and the like); anthraquinone dyes,monoazo dyes, disazo dyes, phthalocyanine derivatives, including variousphthalocyanine sulfonate salts, aza(18)annulenes, formazan coppercomplexes, triphenodioxazines, and the like; and the like, as well asmixtures thereof.

Examples of suitable pigments include black pigments, white pigments,cyan pigments, magenta pigments, yellow pigments, or the like. Further,pigments can be organic or inorganic particles. Suitable inorganicpigments include carbon black. However, other inorganic pigments may besuitable such as titanium oxide, cobalt blue (CoO—Al₂0₃), chrome yellow(PbCr0₄), and iron oxide. Suitable organic pigments include, forexample, azo pigments including diazo pigments and monoazo pigments,polycyclic pigments (e.g., phthalocyanine pigments such asphthalocyanine blues and phthalocyanine greens), perylene pigments,perinone pigments, anthraquinone pigments, quinacridone pigments,dioxazine pigments, thioindigo pigments, isoindolinone pigments,pyranthrone pigments, and quinophthalone pigments), insoluble dyechelates (e.g., basic dye type chelates and acidic dye type chelate),nitro pigments, nitroso pigments, anthanthrone pigments such as PR168,and the like. Representative examples of phthalocyanine blues and greensinclude copper phthalocyanine blue, copper phthalocyanine green, andderivatives thereof (Pigment Blue 15, Pigment Green 7, and Pigment Green36). Representative examples of quinacridones include Pigment Orange 48,Pigment Orange 49, Pigment Red 122, Pigment Red 192, Pigment Red 202,Pigment Red 206, Pigment Red 207, Pigment Red 209, Pigment Violet 19,and Pigment Violet 42. Representative examples of anthraquinones includePigment Red 43, Pigment Red 194, Pigment Red 177, Pigment Red 216 andPigment Red 226. Representative examples of perylenes include PigmentRed 123, Pigment Red 149, Pigment Red 179, Pigment Red 190, Pigment Red189 and Pigment Red 224. Representative examples of thioindigoidsinclude Pigment Red 86, Pigment Red 87, Pigment Red 88, Pigment Red 181,Pigment Red 198, Pigment Violet 36, and Pigment Violet 38.Representative examples of heterocyclic yellows include Pigment Yellow1, Pigment Yellow 3, Pigment Yellow 12, Pigment Yellow 13, PigmentYellow 14, Pigment Yellow 17, Pigment Yellow 65, Pigment Yellow 73,Pigment Yellow 74, Pigment Yellow 90, Pigment Yellow 110, Pigment Yellow117, Pigment Yellow 120, Pigment Yellow 128, Pigment Yellow 138, PigmentYellow 150, Pigment Yellow 151, Pigment Yellow 155, and Pigment Yellow213. Such pigments are commercially available in either powder or presscake form from a number of sources including, BASF Corporation,Engelhard Corporation, and Sun Chemical Corporation. Examples of blackpigments that may be used include carbon pigments. The carbon pigmentcan be almost any commercially available carbon pigment that providesacceptable optical density and print characteristics. Carbon pigmentssuitable for use in the present system and method include, withoutlimitation, carbon black, graphite, vitreous carbon, charcoal, andcombinations thereof. Such carbon pigments can be manufactured by avariety of known methods, such as a channel method, a contact method, afurnace method, an acetylene method, or a thermal method, and arecommercially available from such vendors as Cabot Corporation, ColumbianChemicals Company, Evonik, and E.I. DuPont de Nemours and Company.Suitable carbon black pigments include, without limitation, Cabotpigments such as MONARCH 1400, MONARCH 1300, MONARCH 1100, MONARCH 1000,MONARCH 900, MONARCH 880, MONARCH 800, MONARCH 700, CAB-O-JET 200,CAB-O-JET 300, REGAL, BLACK PEARLS, ELFTEX, MOGUL, and VULCAN pigments;Columbian pigments such as RAVEN 5000, and RAVEN 3500; Evonik pigmentssuch as Color Black FW 200, FW 2, FW 2V, FW 1, FW18, FW S160, FW S170,Special Black 6, Special Black 5, Special Black 4A, Special Black 4,PRINTEX U, PRINTEX 140U, PRINTEX V, and PRINTEX 140V. The above list ofpigments includes unmodified pigment particulates, small moleculeattached pigment particulates, and polymer-dispersed pigmentparticulates. Other pigments can also be selected, as well as mixturesthereof. The pigment particle size is desired to be as small as possibleto enable a stable colloidal suspension of the particles in the liquidvehicle and to prevent clogging of the ink channels when the ink is usedin a thermal ink jet printer or a piezoelectric ink jet printer.

The colorant can be present in the stretchable ink composition in anydesired or effective amount, in embodiments, the colorant can be presentin an amount of from about 0.05 to about 15 percent, or from about 0.1to about 10 percent, or from about 1 to about 5 percent by weight, basedon the total weight of the stretchable ink composition.

Additives.

The stretchable ink composition can further comprise suitable knownadditives as optional additives.

In embodiments, the stretchable ink composition is a low-viscositycomposition. The term “low-viscosity” is used in contrast toconventional high-viscosity inks such as screen printing inks, whichtend to have a viscosity of at least 1,000 centipoise (cps). In specificembodiments, the ink disclosed herein has a viscosity of no more thanabout 100 cps, no more than about 50 cps, or no more than about 20 cps,although the viscosity can be outside of these ranges. When used in inkjet printing applications, the ink compositions are generally of aviscosity suitable for use in said ink jet printing processes.

In embodiments, the stretchable ink compositions have a surface tensionof at least about 22 dynes per centimeter, at least about 25 dynes percentimeter, at least about 28 dynes per centimeter, no more than about40 dynes per centimeter, in another embodiment no more than about 38dynes per centimeter, and or no more than about 35 dynes per centimeter,although the surface tension can be outside of these ranges.

In embodiments, the stretchable ink compositions contain particulateshaving an average particle diameter of no larger than about 5micrometers (μm), no larger than about 2 μm, no larger than about 1 μm,or no larger than about 0.5 μm, although the particulate size can beoutside of these ranges. In specific embodiments, the polyurethaneelastomer is in an emulsion form in the ink, having an average particlediameter of no larger than about 2 μm, no larger than about 1 μm, or nolarger than about 0.5 μm, although the particulate size can be outsideof these ranges.

The ink compositions can be prepared by any suitable process, such as bysimple mixing of the ingredients. One process entails mixing all of theink ingredients together and filtering the mixture to obtain an ink.Inks can be prepared by mixing the ingredients, heating if desired, andfiltering, followed by adding any desired additional additives to themixture and mixing at room temperature with moderate shaking until ahomogeneous mixture is obtained, in embodiments from about 5 to about 10minutes. Alternatively, the optional ink additives can be mixed with theother ink ingredients during the ink preparation process, which takesplace according to any desired procedure, such as by mixing all theingredients, heating if desired, and filtering.

Also disclosed herein is a process which comprises applying an inkcomposition as disclosed herein to a substrate in an imagewise pattern.

The ink compositions can be used in a process which entailsincorporating the ink composition into an ink jet printing apparatus andcausing droplets of the ink to be ejected in an imagewise pattern onto asubstrate. In a specific embodiment, the printing apparatus employs athermal ink jet process wherein the ink in the nozzles is selectivelyheated in an imagewise pattern, thereby causing droplets of the ink tobe ejected in imagewise pattern. In another embodiment, the printingapparatus employs an acoustic ink jet process wherein droplets of theink are caused to be ejected in imagewise pattern by acoustic beams. Inyet another embodiment, the printing apparatus employs a piezoelectricink jet process, wherein droplets of the ink are caused to be ejected inimagewise pattern by oscillations of piezoelectric vibrating elements.Any suitable substrate can be employed.

In a specific embodiment, the process entails printing the ink onto adeformable substrate, such as textile, rubber, rubber sheeting, plastic,plastic sheeting, coated paper, or the like. In some embodiments, thesubstrate is a stretchable substrate, such as textile or rubber sheets.In other embodiments, the substrate is a plastic which is deformable atan elevated temperature higher than the glass transition temperature ofthe plastic, for example, in the process of molding into 3-dimensionalobjects. When the ink disclosed herein is used, the imagewise patternwill not be damaged upon molding. The rubber sheets with the imagewisepattern can be used, for example, as wrap for a 3-D object.

In one embodiment, the inks disclosed herein can be printed on a rubbersubstrate, such as natural polyisoprene, polybutadiene rubber,chloroprene rubber, neoprene rubber, butyl rubber (copolymer ofisobutylene and isoprene), styrene-butadiene rubber, silicon rubber,nitrile rubber (which is a copolymer of butadiene and acrylonitrile),ethylene propylene rubber, ethylene propylene diene rubber,epichlorohydrin rubber, polyacrylic rubber, ethylene-vinyl acetate,polyether block amides, polysulfide rubber, chlorosulfonatedpolyethylene as Hypalon®, or the like. In a specific embodiment, theinks disclosed herein can be printed on a deformable substrate, inembodiments, silicon rubber, polyacrylic rubber, butyl rubber, orneoprene rubber substrate and the imaged substrate can be stretched inone axial direction (i.e., along the x-axis, as opposed to both thex-axis and the y-axis) to, in embodiments, at least 110%, at least 150%,at least 200%, or at least 500% of the length of its original dimension,in embodiments, at least about 50 times, at least about 100 times, or atleast about 500 times, without exhibiting visible cracks ordelamination. In embodiments, the stretchable ink has the characteristicthat an image printed with the stretchable ink composition can bestretched in one axial direction to up to at least 110% along the lengthof its original dimension without exhibiting any visible cracks ordelamination to the naked human eye; or has the characteristic that animage printed with the stretchable ink composition can be stretched inone axial direction to from about 110% to about 500% along the length ofits original dimension without exhibiting any visible cracks ordelamination to the naked human eye.

In embodiments, images generated with the stretchable inks herein arehighly water-resistant. In one embodiment, images generated with theinks exhibit a water droplet contact angle of at least about 80°, atleast about 90°, or at least about 95°, although the contact angle canbe outside of these ranges. The water-resistant characteristic rendersthe ink disclosed herein suitable for outdoor applications or printingon water-related products such vehicle wrap, swimming suits, and thelike.

In a specific embodiment, the images generated with the stretchable inksdisclosed herein have a good chemical resistance. For example, they canexhibit good to excellent resistance toward alcohols, acetic acid,acetamide, allyl bromide, allyl chloride, benzoyl chloride, ethers,esters, hydrocarbons, blood, salt solutions, and the like.

In embodiments, images generated with the stretchable inks disclosedherein have a tensile strength of at least about 1.0 MPa, at least about3 MPa, at least about 4 MPa, at least about 8 MPa, no more than about 25MPa, no more than about 20 MPa, or no more than about 18 MPa, asmeasured by ASTM D412C, in embodiments a tensile strength of at least1.0 MPa and no more than 25 MPa, although the tensile strength can beoutside of these ranges.

In embodiments, images generated with the stretchable inks disclosedherein have an elongation at break of at least about 150%, at leastabout 200%, at least about 400%, no more than about 1000%, no more thanabout 800%, or no more than about 700%, as measured by ASTM 0412C,although the elongation at break can be outside of these ranges.Generally, the images have a larger elongation at break than that of thedeformable substrate.

In embodiments, images generated with the stretchable inks disclosedherein have a hardness (Shore A) value of at least about 20, at leastabout 30, at least about 40, no more than about 100, no more than about90, or no more than about 85, as measured by ASTM 2240, although thehardness can be outside of these ranges.

In embodiments, images generated with the stretchable inks disclosedherein form a continuous layer on the substrate. Therefore, the imageswill have a small color difference with or without stretching. This isin contrast to some conventional stretchable images that are composed ofa dots array. Images based on a discontinuous dots array have poor imagequality, especially upon stretching, for example, the color density willdecrease dramatically. In embodiments, the images generated with thestretchable ink composition herein has a color difference (ΔE) less than5.0, or less than 3.5, or less than 3.0, or less than 2.0, or less than1.0, when stretched in one axial direction to about 150%. It isgenerally known that untrained naked human eyes cannot differentiate thecolors with color difference (ΔE) values of <3.0. Color difference (ΔE)values of >6.0 are considered a very obvious color difference.

In embodiments, images generated with the stretchable inks disclosedherein have an excellent adhesion on various substrates prior to orafter stretching.

In embodiments, a patterned article herein comprises a deformablesubstrate; an image printed on the deformable substrate, the image beingformed from a solventless radiation curable stretchable ink comprisingan aliphatic urethane monomer or oligomer, an acrylic ester monomer, andan optional colorant. In a specific embodiment, the printed image can bestretched along one axis to at least 110% of the length of its originaldimension without exhibiting visible cracks or delamination from thedeformable substrate. In another embodiment, the image printed with thestretchable ink composition has a color difference less than 3.0 whenstretched in one axial direction to about 150% relative to anon-stretched printed image.

EXAMPLES

The following Examples are being submitted to further define variousspecies of the present disclosure. These Examples are intended to beillustrative only and are not intended to limit the scope of the presentdisclosure. Also, parts and percentages are by weight unless otherwiseindicated.

Commercially available oligomer CN3001 from Sartomer (Exton, Pa.), aclass of aliphatic urethane oligomer, was initially identified as anelastomeric material after self-curing tests. It was stretchable up tothe maximum elongation of the tested latex rubber substrate. To getwithin the desired viscosity range for jetting, various acrylatemonomers were added to the oligomers. The monomers chosen had thecriteria of low viscosities and low glass transition temperature toretain the elasticity of the oligomer. CD420 (also commerciallyavailable from Sartomer), a class of small molecule acrylic estermonomer, was used to lower the viscosity.

A problem with films prepared from both CN3001 and CD420 was the largedegree of tackiness. While the entire coating was solid after the cure,and it appeared no residual monomer remained by the absence of materialtransferred after contact, the film was very tacky. It was discoveredthat the tackiness was a material property of the two component mixtureof CN3001 and CD420 after investigating both the curing exposure timeand initiator concentrations. To lower the tackiness, a third componentwas identified and introduced to increase the density of the hardsegments and to improve the surface properties without limiting theelasticity. Oligomer CN3105 (also commercially available from Sartomer)which is a class of acrylic oligomer with methacrylate acid ester,acrylic ester and aromatic urethane acrylate, or monomeracryloxypropyltrimethoxysilane was identified and used to increasedensity of hard segments and to lower surface tackiness.

Therefore, in embodiments, a specific combination of components providedwhich provided a desired combination of properties including elasticity,surface tack, ink viscosity and printing quality, a final optimizedformulation was discovered. In further embodiments, a specificcombination of components provided in a specific ratio was discoveredwhich provided a desired combination of properties including elasticity,surface tack, ink viscosity and printing quality. Exemplary inks havingthe formulations as shown in Table 1 were prepared and printed using aDimatix™ piezoelectric printer.

TABLE 1 Solventless Radiation Curable Stretchable Ink Example 1 Example2 Component Weight % Component Weight % Irgacure ® UV10 0.2% Irgacure ®UV10 0.2% Irgacure ® IC819 1.0% Irgacure ® IC819 1.0% Irgacure ® IC1273.5% Irgacure ® IC127 3.5% CN3001 33.0% CN3001 33.0% CN3105 14.0%Acryloxypropyltrimethoxysilane 9.5% CD420 47.3% CD420 51.8% Pigment Blue15 (copper 1.0% Pigment 1.0% phthalocyanine) Viscosity Range (mPa-s)12.1-11.9 Viscosity Range (mPa-s) 10.6-8.2 Avg Viscosity @ 50° C.(mPa-s) 12 Avg Viscosity @ 50° C. 9.4 (mPa-s)

Inks of both formulations had the best printing performance at 20 μmdrop spacing. The Example 1 ink had the best printing performance at 55°C., and the Example 2 ink was best printed at 40° C. Inks of bothformulations had exemplary lifetime once loaded in the print head, withall nozzles working and remaining unclogged.

Images were printed onto plasma cleaned latex and silicone substratesaccording to the optimized parameters. The two substrates were purchasedfrom commercial sources and cleaned before printing. They were rinsedwith isopropyl alcohol (IPA) solvent before being plasma cleaned for 1minute in air plasma. The inks were printed in a 4 centimeter by 4centimeter square, with two printing passes before curing. Both inks hadvery good adhesion on the silicone and latex substrates. The cured imagewas intact and unaffected by multiple stretching cycles and vigorousrubbing of the image. Tape test was conducted to verify the adhesionusing scotch tape. All films passed the tape adhesion test, even on thesilicone substrate after multiple stretching cycles. This was a greatachievement as silicone rubber is notoriously difficult for a printedfilm to adhere to. Images corresponding to the printed cured films ofExample 1 and Example 2 on silicone and latex, as well as their tapetest after stretching are shown below.

It will be appreciated that various of the above-disclosed and otherfeatures and functions, or alternatives thereof, may be desirablycombined into many other different systems or applications. Also thatvarious presently unforeseen or unanticipated alternatives,modifications, variations or improvements therein may be subsequentlymade by those skilled in the art which are also intended to beencompassed by the following claims. Unless specifically recited in aclaim, steps or components of claims should not be implied or importedfrom the specification or any other claims as to any particular order,number, position, size, shape, angle, color, or material.

The invention claimed is:
 1. A solventless radiation curable stretchableink composition comprising: an aliphatic urethane monomer or oligomer;an acrylic ester monomer; a photoinitiator; and an optional colorant;wherein the stretchable ink after curing has a tensile strength of atleast 1.0 MPa and no more than 25 MPa.
 2. The radiation curablestretchable ink composition of claim 1, wherein the aliphatic urethanemonomer or oligomer is present in an amount of from about 15 to about 50weight percent based on the total weight of the ink composition.
 3. Theradiation curable stretchable ink composition of claim 1, wherein thecolorant is selected from the group consisting of dyes, pigments, andcombinations thereof.
 4. The radiation curable stretchable inkcomposition of claim 1, wherein the radiation curable stretchable inkcomposition is an ultra-violet radiation curable ink composition.
 5. Theradiation curable stretchable ink composition of claim 1, wherein theacrylic ester monomer is present in an amount of from about 30 weightpercent to about 70 weight percent based on the total weight of the inkcomposition.
 6. The radiation curable stretchable ink composition ofclaim 1, having the characteristic that an image printed with thestretchable ink composition can be stretched in one axial direction toup to at least 110% along the length of its original dimension withoutexhibiting any visible cracks or delamination to the naked human eye. 7.The radiation curable stretchable ink composition of claim 1, furthercomprising: an acryloxyalkylsilane.
 8. The radiation curable stretchableink composition of claim 7, wherein the acryloxyalkylsilane is presentin an amount of from about 5 weight percent to about 20 weight percentbased on the total weight of the ink composition.
 9. The radiationcurable stretchable ink composition of claim 1, further comprising: anacrylic oligomer comprising a member of the group consisting ofmethacrylate acid ester, acrylic ester, aromatic urethane acrylate, andcombinations thereof.
 10. The radiation curable stretchable inkcomposition of claim 9, wherein the acrylic oligomer is present in anamount of from about 5 weight percent to about 30 weight percent basedon the total weight of the ink composition.
 11. A solventless radiationcurable stretchable ink composition comprising: an aliphatic urethanemonomer or oligomer; an acrylic ester monomer; a photoinitiator; and anoptional colorant; having the characteristic that an image printed withthe stretchable ink composition can be stretched in one axial directionto up to at least 110% along the length of its original dimensionwithout exhibiting any visible cracks or delamination to the naked humaneye.